Ever Seen a Bumble Bee Nest?

Ever seen a bumble bee nest?

We remember when insect enthusiast Rita LeRoy of the Loma Vista Farm, part of the Vallejo City Unified School District, found the nest of the yellow-faced bumble bee, Bombus vosnesenkii, in May of 2015. They were buzzing in and out, providing nectar and pollen for the growing colony.

However, as we all know, overwintering bumble bee nests are even more difficult to find. The queen is hibernating, getting ready to emerge next spring to start a new colony.

And now comes newly published research led by the Neal Williams lab, UC Davis Department of Entomology and Nematology, on Fantastic Bees and Where to Find Them: Locating the Cryptic Overwintering Queens of a Western Bumble Bee.

Published Nov. 20, 2019 in Ecosphere, an open access journal of the Entomolgoical Society of America, it is drawing the attention it should.

The abstract:

"Bumble bees are among the best-studied bee groups worldwide, yet surprisingly we know almost nothing about their overwintering habitats nor the microsite characteristics that govern selection of these sites. This gap represents a critical barrier for their conservation, especially if preferred overwintering habitats differ from foraging and nesting habitats. Current conservation plans focus on foraging habitat, potentially creating a problem of partial habitats where improved forage might fail to prevent population declines due to limited overwintering sites. We provide the first data on the overwintering habitat for any western North American bumble bee. Our data suggest that overwintering and foraging habitats are likely distinct, and queens' selection of overwintering sites may be shaped by environmental stressors of the year. In our study area, queens overwintered in litter beneath cypress trees, where no floral resources exist. Whether this separation of overwintering and foraging habitat holds for other bumble bee species remains to be discovered. Our data highlight the need to consider the whole life cycle for understanding population dynamics and conservation planning. This need is underscored by growing evidence for the decline of multiple North American bumble bee species."

They detailed how they "looked for overwintering queens on California's central coast. We spent ~80 person-hours searching different ground covers around abandoned military barracks at former Fort Ord Military Base where we previously observed large numbers of nest-searching queen Bombus vosnesenskii Radoszkowski and B. melanopygus Nylander."

"Ground cover at Fort Ord is typical of the central California coast: a patchwork of grassy meadow, mats of non-native ice plant (Carpobrotus edulis), and small stands of Monterey cypress (Cupressus macrocarpa) and Monterey pine (Pinus radiata). In December 2018, we searched for bumble bee queens by carefully digging the vegetative, litter, and soil strata of grassy meadow, ice plant mat, and the needle litter under two cypress and two pine tree."

What did they find and learn? It's well worth the read: https://doi.org/10.1002/ecs2.2949